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141.
Katrin Hartl Karl J.J. Mayrhofer Marco Lopez Dan Goia Matthias Arenz 《Electrochemistry communications》2010,12(11):1487-1489
In the presented work, the evaluation of an unsupported AuPt core–shell catalyst for the oxygen reduction reaction is introduced. Applying only basic chemicals in an upscalable synthesis route, it is demonstrated that uniform, flat, and complete Pt layers around a spherical Au core are obtained. The electrocatalytic measurements show that the surface area specific activity of the AuPt core–shell catalyst towards the important oxygen reduction reaction equals the one of polycrystalline bulk Pt. To our knowledge, this is the first time that the unfavorable particle size effect of Pt nanoparticles could be by-passed for a nanoscale catalyst. 相似文献
142.
Zoltán M. Balogh Katrin Fässler Ioannis D. Platis 《Journal d'Analyse Mathématique》2011,113(1):265-291
We develop a method using the modulus of curve families to study minimisation problems for the mean distortion functional in the class of finite distortion homeomorphisms. We apply our method to prove extremality of the spiral-stretch mappings defined on annuli in the complex plane. This generalises results of Gutlyanskiĭ and Martio [12] and Strebel [23]. 相似文献
143.
Masahiko Yoshimura Michael Dieckmann Alexandre Lumbroso Raymonde Fonné-Pfister Claudio Screpanti Katrin Hermann Stefano Rendine Pierre Quinodoz Alain De Mesmaeker 《Helvetica chimica acta》2023,106(10):e202300111
Strigolactones are one of the phytohormones, which have multiple activities on plant growth and development. Since these strigolactone activities are highly associated with crop yield, use of strigolactone could be a promising technology in modern sustainable agriculture. The major strigolactones in corn root exudates have been identified as zealactone 1a/b and zeapyranolactone. We recently disclosed the first total synthesis of zealactone 1a/b together with its biological activity in corn. Herein, we describe the design and synthesis of simplified analogues of both corn-derived strigolactones with their bioavailability in soil and their biological activities. These compounds would be potential leads for the development of synthetic strigolactones for the agronomical use in a more sustainable crop production. 相似文献
144.
We study isometric embeddings of a Euclidean space or a Heisenberg group into a higher dimensional Heisenberg group, where both the source and target space are equipped with an arbitrary left-invariant homogeneous distance that is not necessarily sub-Riemannian. We show that if all infinite geodesics in the target are straight lines, then such an embedding must be a homogeneous homomorphism. We discuss a necessary and certain sufficient conditions for the target space to have this ‘geodesic linearity property’, and we provide various examples. 相似文献
145.
Philipp Rietsch Dr. Sebastian Sobottka Dr. Katrin Hoffmann Dr. Alexey A. Popov Pascal Hildebrandt Prof. Dr. Biprajit Sarkar Dr. Ute Resch-Genger Prof. Dr. Siegfried Eigler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17361-17365
Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches. 相似文献
146.
Alan R. Katritzky Stanislaw Rachwal Bogumila Rachwal John W. Frankenfeld 《国际化学动力学杂志》1995,27(4):351-357
The 1H NMR technique was applied for the measurement of the isomerization rates of N-ethyl-N-[(benzotriazol-1-yl)methyl]aniline ( 4 ) and 4-butyl-N-[(benzotriazol-1-yl)methyl]aniline ( 7 ) to the corresponding benzotriazol-2-yl isomers in dioxane-d8 at 35°C. The rate constants obtained for pure dioxane-d8 were 1.62 and 0.28 h?1 for 4 and 7 , respectively. For both compounds, addition to acetic acid to the dioxane solutions accelerated the isomerizations whereas addition of triethylamine retarded it strongly. Addition of water slowed the isomerization of 4 but accelerated that of 7 : the different effects operating in the two cases are discussed and rationalized. © 1995 John Wiley & Sons, Inc. 相似文献
147.
148.
Katrin Tent 《Advances in Mathematics》2004,181(2):308-320
Let G be a group with an irreducible spherical BN-pair of rank 2 where B contains a normal nilpotent subgroup U with B=U(B∩N). Then G is essentially a group of Lie type. This completes the classification of split BN-pairs of rank 2, generalizing the corresponding result for finite groups due to Fong and Seitz. 相似文献
149.
Katrin Schumacher 《Acta Appl Math》1992,28(3):296-297
Book Reviews
Ordered algebraic structuresJorge Martinez (ed.): Proceedings of the Caribbean Mathematics Foundation Conference on Ordered Algebraic Structures, Curaçao, August 1988, Mathematics and Its Applications, vol. 55, Kluwer Academic Publishers, Dordrecht, Boston, London, 1989, xx + 278 pp., ISBN 0-7923-0489-6, US$ 104. 相似文献150.